SWR calibration waaay off the chart

A manual link is at the bottom of this entry. Troubleshoot the problems you've described:

Meter Not Working:
The needle moving slightly to the right when you key the mic could be due to incorrect calibration. Make sure to recalibrate the meter according to the manual instructions. If you calibrated it differently, that might cause the needle to go against the right side of the meter.

Recalibrating the meter should resolve this issue.
Meter Light Problems:
If the meter light isn't working, consider replacing the LED. Sometimes, a burnt signal meter light can occur. Replacing the LED should fix this.

SWR Meter Not Working:
Incorrect SWR calibration or bumping the calibrated knob might cause the SWR meter to malfunction.
To check the SWR meter:
Turn on the SWR calibrate knob until it keys up all the way at the end.
Switch to SWR mode and key the mic.
If the needle barely moves, turn down the Dynamike knob.
Finally, switch back to S/RF mode.

No Receiving Audio:
If you're not receiving audio, check the following:
Ensure the squelch knob is adjusted correctly. Start with the knob counterclockwise and turn it slowly clockwise until white noise stops.
Verify that the microphone is working properly. You can try a different mic to rule out any mic-related issues.
Make sure the radio is on the correct channel for transmitting and receiving.
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Calibrating the SWR (Standing Wave Ratio) meter on your Cobra Classic 29zLtd CB radio is essential for optimal antenna performance. Follow these steps to calibrate it properly:

Prepare the Setup:
Park your vehicle at least 20 feet away from trees and buildings.
Close all doors, hood, and trunk.

Choose the Channel:
Select the channel you want to check. It's recommended to test on channels 1, 20, and 40.

SWR Calibration:
On the radio, press the SWR/CAL button until the display shows "CAL."
While pressing the transmit button on the microphone, turn the SWR CAL knob (the last knob on the right) until the meter needle aligns with the "CAL" mark.
Release the transmit button.

Switch to SWR Mode:
Push the SWR/CAL button again until the display shows "SWR."

Read the SWR:
Press the transmit button on the microphone.
Observe the SWR reading on the top scale of the meter.
Ideally, the SWR should be below 3. Lower values are better.
Remember that SWR is a measure of antenna performance, and poor SWR can be caused by the antenna, antenna cable, or installation. Adjust the antenna length to achieve similar SWR readings on channels 1 and 40 while keeping it below 3. Most antennas are adjustable; refer to the manufacturer's instructions for specific adjustments. cobra-29ltdclassic-cb-radio-user-manual.pdf (roadtrucker.com) MANUAL

1. You calibrate the antenna to match the CB rather than the other way around. Some antennas can be adjusted while others cannot. This should not cause a problem since the ones that cannot be adjusted generally don't need adjusting. The ones that can be allow for fine tuning to get a better match.

2.To match your antenna to your CB you set the SWR (Standing Wave Ratio) to it's lowest possible setting. SWR is the ratio of power that gets out through your antenna versus the reflected power that gets sent back to the CB. You want to get the most power to go out, or forward, through the antenna as this drives the signal that others receive. To set your SWR;

3.Connect an SWR meter between the antenna and the CB using a short piece of Co-ax cable. Set the switch on the meter to Forward Power. Key the CB and adjust the dial on the SWR meter until the needle of the meter is fully forward. Release the transmit button and change the switch on the swr meter to Reflected Power. Key the mic again and note how high the needle goes. If the needle doesn't go into the red it's safe to use but the lower the reading the better.

4. To bring it down check your antenna. Some antennas have a telescopic tip that can be extended or reduced by loosening a nut near the top. Try extending it fully and repeat the procedure at paragraph 3 above. If your SWR rises then try reducing the antenna length and check again. It's a matter of finding where you get the lowest swr by making smaller adjustments from the best of the 3 settings above.

5. You'll probably find that when you get a low SWR on one channel it will be higher on other channels. This is because of the frequency difference. Unless you use one channel nearly all the time, it's best to set the swr on the middle channel so if you have a 40 channel CB set the SWR on channel 20. The further you change up or down the higher the SWR will increase but it should be still within the safe range. If you set the SWR on say channel 1 the SWR will be twice as high when you change to channel 40 than it would have been if you set it on channel 20.

6. Most people never check their SWR so if you're using a commercial CB antenna, rather than a home made one, it should be factory set to give a reasonable match so if yours cannot be adjusted it's probably matching ok. A more common problem to look out for is the connection from the antenna to the CB. Make sure that the screening wire and the centre core are not touching. Even a single strand of the screening touching the centre wire will cause screeching on your transmission and before long will cause your CB to stop working. 73s and enjoy your CB.

is she getting bad motor noise? Make sure the ANL is on. Is the antenna tuned for best SWR? if the antenna is not tuned it can effect the receive.

Try checking the SWR's on channel 1, 20, and 40. The SWR's will change from the low channels to the mid channels to the high channels. The key is to make sure that the SWR's are around 1 or less at all three points. If the light goes out when checking one of them, then the problem is most likely the SWR's. If the light stays on when checking these channels, the issue might still be the SWR's but I would look at the grounding on the antennas. When holding the talk button on the mic and switching from calibrate to swr, can give a false reading. This is due to the calibrate circuit remaining open until you release the talk button. Take the SWR reading by releasing the Talk button on the mic after calibrating then pressing the talk button again after switching back to SWR. This will be the most accurate reading. From everything you described, I would be looking for a grounding problem with the antennas or coax, possibly even a rub though on the coax somewhere in the dash.

Your SWR is probably NOT fine. You need to use an external meter if you have had work done to the radio. Especially if you have had a swing mod done to the radio. When you do this, the dead key of the radio is lower then the calibration knob on the radio can adjust for. It will always come up lower then it actually is.

Your radio might have been fine before the work was done on it because it was putting out very little power. Now you are most likely putting out 50 watts or more. Big jump from 4 watts.

When your raise the power in a radio, you will notice more when the antenna is not properly tuned.

In most cases with a stock CB, even when the antenna is not even near tuned, you will get a reading less then 1.5 anyway.

the more power you put out, the more important it is to have a good match.

But an external SWR meter, and check it. be careful if the ANT light is on.

You might also want to check your coax, connections to it, and your antenna for anything wrong.

You should not calibrate the antenna before you install it on the car!! the antenna needs to be calibrated on the vehicle that it is going to be on. Type of vehicle, different mounts, and many other variables can change the amount of reflection you will get.

j0hn9999 did a much better job but left some info out.

Take your SWR readings on channel 1, then on channel 40.... NOW, if your SWR is higher on ch 40 then ch 1, then your antenna is too long and it needs to be shortened. Refer to the antenna instructions on how to shorten the antenna.

If your SWR is higher on ch 1 then on ch 40 then your antenna is too short. You must lengthen the antenna. Again refer to your antenna instructions on how to lengthen your antenna.

You must calibrate each time you take a reading.

Make sure your doors and windows are shut when taking a reading

Make sure you are in an open lot when taking a reading as buildings, trees and other structures can cause reflection and give you an inaccurate reading.

If you adjust the length of your antenna on another vehicle and then put it on yours, the SWR will be off. It will need to be tuned again.

An external meter is better then the one in the radio, but will need to be hooked up in the vehicle you have the antenna on.

If you are not running any kind of power, or do not have a swing kit installed, and the radio is stock, the meter in the radio is more then enough to get a correct SWR reading.

You need expensive radio test gear to attempt what you want to do. You can not do this with an SWR meter
GOOD LUCK

The red light always comes on while mic is keyed. It is designed to do that. It will blink on and off while mic is keyed if there is a SWR problem. This is explaned in operaters manual.

double check your connections and your cable for shorted PL 259 connectors. Oil filled antenna! Humm Sham on you if you are using a liner! Oh and quit sniping the antenna remember the higher in frequincy the shorter the antenna and longer for lower in frequincy. So it could be just where the antenna is located some antennas work good there but a diferent one wont try another spot also make sure your in a clear area when checking SWR not your drive way next to the garage or house or other car and finaly use an external SWR meter the ones on the radio some times SUCK.

If the antenna is tunable, you definitely need to start out by having the swr set properly on the antenna. Also, make sure the plastic ferrel, (the small round white piece) is between the top of the antenna bracked and the antenna itself. It is there to make sure the antenna does not ground out to the vehicle. If the antenna is grounding out, it will be like no antenna at all. I have also had a few customers that have had broken coaxes straight out of the factory package on cheaper antenna setups.

Dean
Rollin CBs